Adhesion of plastic material of the dental type to metallic dental prosthesis articles or components, which may form a main structural frame of the final dental prosthesis presents some problems. Recently, methods have been proposed in which, to improve the adhesion, a silicon oxide-containing adhesion-promoting layer is applied to the metallic dental prosthesis part.
One process is described in the publication "Dental-Labor XXX". According to this publication, a glow discharge device is used. The metallic prosthesis part is placed into an evacuated chamber in which, under a pressure of between about 0.133 to 0.4 mbar, a glow discharge plasma is generated. A silicon compound, such as triethyloxymethylsilane, is added to the glow discharge plasma.
Another method is described in U.S. Pat. No. 4,364,731. To coat a metallic dental prosthesis part with a silicon oxide adhesion-promoting layer, a magnetron sputtering apparatus is suggested, operated at radio frequency. A pressure of 10.sup.-3 mbar is used. The silicon oxide is sputtered off high-purity quartz glass and deposited on the dental prosthesis part located in the vacuum chamber.
All apparatus heretofore proposed, and all the methods, are expensive, and equipment-intensive. The methods and apparatus all utilize evacuated chambers within which the dental prosthesis parts are coated.